• T. Hara, H. Tanaka, K. Togawa
  RIKEN/SPring-8, Hyogo

To realize a compact FEL facility, a high frequency accelerator is indispensable to shorten the accelerator length. Then, a high-harmonic cavity used for nonlinear correction of a beam energy chirp encounters a technological difficulty of extremely high frequency RF system. In order to overcome this difficulty, a method of over-correction is proposed. In this method, a correction cavity is installed before any bunch compressors. Since the effective frequency of the correction cavity is increased as the electron bunch length compressed, the same RF frequency as main accelerators can be used for the correction cavity.

Slides

• H. Tanaka, T. Fukui, T. Hara, N. Hosoda, T. Inagaki, S.I. Inoue, T. Ishikawa, H. Kitamura, C. Kondo, N. Kumagai, H. Maesaka, M. Nagasono, T. Ohshima, Y. Otake, T. Sakurai, T. Shintake, K. Shirasawa, T. Tanaka, K. Togawa, K. Tono, M. Yabashi
  RIKEN/SPring-8, Hyogo
• T. Hasegawa, Y. Kano, T. Morinaga, H. Ohashi, Y. Tajiri, S. Takahashi, S. Tanaka, T. Togashi, M. Yamaga, R. Yamamoto
  JASRI/SPring-8, Hyogo-ken

Stable SASE FEL has been routinely used for user experiments since May 2008 at the SCSS test accelerator, which was constructed to perform a proof-of-principle experiment towards realization of a compact and high performance XFEL facility. In FY2008, a beam time of 840 hr (95 days) was provided to 11 research groups with a downtime rate of ~4%, a pulse energy of ~30μJ and an intensity fluctuation of ~10% in STD. A feature of our stable operation is power-saturated SASE FEL kept over a full operation period

1. in spite of a day-by-day operation,
2. without a complicated beam feedback control, and
3. without hard maintenance.

Slides